Abstract: The child welfare system may be the locus of a vicious circle of intergenerational substance use. In the U.S. some 8.3 million teens dependent on alcohol or otherwise needing treatment for substance use actually reside with substance-abusing parents who were maltreated as children. Maltreated children of parents who abuse substances are more likely to abuse substances in adulthood. Teens involved in CWS have an abundance of risk factors and few protective factors against substance abuse. Given the abundance of risk for CWS involved teens, CWS can serve as an important gateway to substance abuse prevention services. CWS has the potential to serve as a robust non-specialty service sector platform because it can facilitate targeting of high risk youth, sustain both preventive and substance abuse treatment programs, and allows for the capture of teens and their caregivers in a mandated treatment setting. The literature on predictors of substance use initiation and intensity among CWS involved teens is still emerging, as is the literature on prevention and treatment services. Therefore, the overall goal of the proposed research is to conduct analyses of an extant national probability cohort of child welfare involved teens to determine the prevalence and impact of substance use, predictors of substance abuse over the course of adolescent development, and the role that current child welfare services play in ameliorating substance use and abuse. To accomplish this goal, we propose a three year study in response to PAR-10-018, Accelerating the Pace of Drug Abuse Research Using Existing Epidemiology, Prevention, and Treatment Research Data, which highlights: 1) basic science development related to knowledge of risk and resilient trajectories of drug using behaviors among CWS teens; and 2) analyses of the organizational and system contexts that improve the accessibility, utilization, and, effectiveness of substance abuse prevention services within a non-specialty sector. The overall goal will be addressed by the following specific aims: 1) Investigate prevalence and longitudinal trajectories of initiation and intensity of substance use among teens in CWS; 2)Investigate predictors of substance use for teens in CWS; 3) Identify common points for entry into substance abuse services, service utilization patterns, and service utilization outcomes for teens in CWS; and 4) Develop a prevention intervention framework for selecting and fitting evidence based interventions to address substance use among CWS involved teens.